5. What is the purpose of stored procedures and triggers in a relational database, and how do they differ from regular SQL queries?

Stored procedures and triggers are both database objects which contain a set of SQL statements that are stored in the database. They are used to encapsulate a sequence of operations, allowing them to be executed with a single call. This can make it easier to manage complex operations, as well as improving performance by reducing the amount of information that needs to be sent between the database and the application.

The purpose of stored procedures is to control data access and manipulation, ensuring data integrity and consistency. They can be used to perform a variety of tasks, such as validating input data, performing calculations, and modifying database structures. Stored procedures can be called explicitly by the application.

Triggers, on the other hand, are used to automatically perform a specific action when certain events occur in the database, such as inserting, updating, or deleting data. They are often used to enforce business rules and data integrity, or to update related tables when a change occurs.

The main difference between stored procedures, triggers, and regular SQL queries is when and how they are executed. Regular SQL queries are executed immediately when they are sent to the database. Stored procedures are stored in the database and must be called by the application to be executed. Triggers are also stored in the database, but they are automatically executed, or "fired," when a specified event occurs.

In terms of their functionality, regular SQL queries are typically used for simple, one-off operations, such as retrieving or updating a single record. Stored procedures and triggers, on the other hand, are used for more complex operations that involve multiple steps or require conditional logic.